<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>视频</title>
</head>
<style>
    .bottona{
        text-align: center;
    }
</style>
<body>
<div class="bottona">
    <button onclick="playPause()">播放/暂停</button>
    <button onclick="makeBig()">大</button>
    <button onclick="makeNormal()">中</button>
    <button onclick="makeSmall()">小</button>
</div>
<video id="video1"  style="width: 420px; margin-top: 15px">
    <source src="img/12.mp4">
</video>

</body>
<script type="text/javascript">
    var myVideo = document.getElementById("video1")
    function playPause() {
        if (myVideo.paused)
            myVideo.play();//播放
        else
            myVideo.pause();//暂停
    }
    function makeBig() {
        myVideo.width=560;
        myVideo.height=633;
    }
    function makeSmall() {
        myVideo.width=320;
    }
    function makeNormal() {
        myVideo.width=420;
    }
</script>
</html>